HPS/MH Lamps 800-900 Watts: High-Power Lighting for Your Indoor Grows
HPS and MH lamps of 800-900 Watts represent the high-end of traditional indoor grow lighting. This power range is for experienced growers managing significant grow spaces, typically between 1.5 and 2.5 m². With their intense light output and adapted spectrum, these lights offer impressive yields for those who master their use.
Why choose 800-900 Watt HPS/MH lighting?
Frankly, when we talk about 800-900 Watts, we're entering the big leagues. These lamps deliver a luminous flux of 110,000 to 140,000 lumens depending on the model, which is more than enough to saturate a 2m x 1.2m space with light. HPS lamps of this power excel in flowering with their red-orange spectrum that boosts resin production and bud density. MH lamps, on the other hand, dominate in vegetative growth with their blue-rich white light that promotes compact and vigorous development.
The main advantage? Light penetration. Unlike LEDs, which can sometimes struggle with the lower parts of tall plants, a 900W HPS literally penetrates the foliage. The result: even the lower branches produce well. This is particularly noticeable with sativa varieties that can reach 1.5m under these lights.
In terms of cost, that's where it gets interesting. The initial investment remains moderate compared to equivalent LEDs, and the lifespan of an HPS/MH bulb is around 10,000 to 15,000 hours depending on quality. For a grower who masters their ventilation and cooling, the return on investment is quickly realized.
How to choose your 800-900 Watt lamp
First criterion: available space. An 800W effectively covers 1.5m², a 900W can go up to 2.2m² if ceiling height allows. Allow a minimum of 60cm between the lamp and the top of the plants, more if your extraction isn't top-notch.
Regarding ballasts, two schools: magnetic or electronic. Electronic ballasts consume 10-15% less, generate less heat, and allow for a smoother start-up of bulbs. They cost more but pay for themselves on the electricity bill. Magnetic ballasts remain reliable and cheaper to buy, perfect for starting out in this power range.
Ventilation is critical. A 900W HPS emits approximately 3000 BTU/h of heat. Plan for an extractor of at least 600 m³/h for a 2m² tent, plus an acoustic duct if you want to sleep soundly. An air-cooled reflector becomes almost mandatory above 800W, unless you're growing in winter in an unheated room.
Last point: bulb quality. Between a generic bulb and a Philips Son-T or Osram Plantastar, the difference in luminous flux can reach 20%. Over a 3-month grow, this directly impacts the final yield.
Frequently Asked Questions
What size grow tent is suitable for an 800-900 Watt HPS/MH lamp?
For an 800W, aim for a tent of 150x150cm or a maximum of 120x200cm. A 900W can cover up to 150x200cm if you have at least 2.2m of total height. Below these dimensions, you waste energy. Above, the light becomes insufficient at the edges, and the center will be too intense. The golden rule: 400-500W per m² to optimize yield without scorching your plants.
LED or HPS/MH, which to choose for 800-900 Watts in flowering?
800-900W HPS lamps remain formidable in flowering thanks to their red-orange spectrum which stimulates terpene production and flower density. A 900W HPS generally produces 15-20% more than an equivalent LED in PPFD, but consumes 30-40% more electricity. Modern LEDs are catching up in terms of yield, generate less heat, and last longer. The choice depends on your initial budget, your electricity bill, and your ability to manage heat.
How to install an 800-900 Watt lamp without overheating my indoor grow?
The key is extraction. Count on a minimum of 600 m³/h for an 800W, 750 m³/h for a 900W. Install an air-cooled reflector with a minimum 150mm duct, connected directly to the extractor. Place the intake at the bottom opposite the extraction, creating an airflow that crosses the entire tent. Keep 60-80cm between the lamp and plants depending on the season. A thermostat controlling the extractor automatically maintains the temperature between 24-26°C during the day.
What is the monthly electricity consumption of an 800-900 Watt lamp in daily use?
An 800W actually consumes 850-900W with the ballast, which is about 306-324 kWh per month for 12h/day. At €0.18/kWh, that represents €55-58 monthly. A 900W goes up to 950-1000W actual, or 342-360 kWh/month, about €62-65. Add €15-25 for ventilation depending on your extractor. In an 18h cycle (vegetative growth), multiply by 1.5. These figures do not include heating, dehumidifier, or other ancillary equipment.
How to maintain and clean an 800-900 Watt HPS/MH lamp to make it last a long time?
Clean the reflector every 3-4 weeks with isopropyl alcohol and a microfiber cloth. A dirty reflector can lose 30% efficiency. Change the bulb every 3-4 cycles even if it still lights up: the luminous flux gradually decreases. Check electrical connections every 6 months, especially with ambient humidity. For electronic ballasts, regularly dust the ventilation grilles. A well-maintained lamp retains 90% of its efficiency for 2-3 years of intensive use.
